Scale model building

[wallfish 19,323]

20 hours ago, ebinmaine said:

I've been mulling how to create a rounded look at the rear and haven't come up with a method that's within my current skill set. So, flat backed it is. 

Just spit balling again

Is the rest of that tank sealed except the front? As in, heat that flat piece you made and blow pressure into the tank. Maybe a damp rag /paper towel wrapped on the tank edge near it to keep that from heating and expanding too

[ebinmaine 77,349]

15 minutes ago, wallfish said:

Just spit balling again

Is the rest of that tank sealed except the front? As in, heat that flat piece you made and blow pressure into the tank. Maybe a damp rag /paper towel wrapped on the tank edge near it to keep that from heating and expanding too

 

 

Decent idea but no... the tank is far from sealed. It is, in fact, not at all joined well. 

To some extent that's the fault of the kit(s) but also, I'm doing a combo that the manufacturer wouldn't have planned.  

 

[wallfish 19,323]

1 hour ago, ebinmaine said:

 

 

Decent idea but no... the tank is far from sealed. It is, in fact, not at all joined well. 

To some extent that's the fault of the kit(s) but also, I'm doing a combo that the manufacturer wouldn't have planned.  

 

How a bout, Make a thin metal cylinder just a bit larger than what the final cut out shape is, glue a piece to it and do the heat air pressure thing. Then cut out the smaller correct size out of that?

Thin aluminum flashing is pretty easy to shape.

[ebinmaine 77,349]

2 minutes ago, wallfish said:

How a bout, Make a thin metal cylinder just a bit larger than what the final cut out shape is, glue a piece to it and do the heat air pressure thing. Then cut out the smaller correct size out of that?

Thin aluminum flashing is pretty easy to shape.

 

This may be combined with carving from wood/clay or bondo.  

[wallfish 19,323]

39 minutes ago, ebinmaine said:

 

This may be combined with carving from wood/clay or bondo.  

What about just making a small metal ring the shape and size it needs to be, thickness would depend how deep you want the concave to be. Lay the plastic material over it and heat the center. Push down if necessary.

 

Or heat the material, lay it right on the actual piece and push to concave it. Once cool and hard flip it over and cut out the shape 

 

I don't know how soft that material will get

Edited Friday at 12:03 AM by wallfish

[Achto 31,016]

One idea that may be adaptable on a smaller scale.

 

[ebinmaine 77,349]

30 minutes ago, wallfish said:

making a

 

It's the crafting of the mold that's exactly the challenge for me. 

 

The tank end is wider than tall.

The middle of the crown needs to be maybe a 1/4" out?

I don't have the artistic skills or tools to make a concave or bowl with the two different angles - much less literal dozens of angles from top to side. 

 

That's why I like the idea of using clay or bondo. 

Perhaps cut out another flat oval. Lay/glue a 1/4" stub in the center. Use that to line up to the edges by molding a softer material. 

Sand/shape from there.  

 

 

 

[ebinmaine 77,349]

34 minutes ago, Achto said:

idea

Very cool! 

[ebinmaine 77,349]

The rear third didn't set just right yesterday so I did some readjusting to the seam. A little more grinding on the plastic at the top. 

Stuck it back together and let it rest for a while. When it felt strong enough I started laying down/in/on/out some filler.  

 

 

 

[8ntruck 8,606]

I'm guessing that you don't need very much dome contour in your tank end.

 

You might be able to use some #8 or #10 solid copper wire formed to the desired oval outline of the tank end, then using a heat gun to heat your plastic sheet sitting on top of the formed wire until soft enough to sag into a shallow dome shape.  Thin sheet .010" or .020" thick should work for this.  Some encouragement may be necessary, though.

[ebinmaine 77,349]

Experimenting with the styrene forming this morning. I found a kitchen spoon with very good contours. 

To get this to work I'd have to make two molds of the end and join them. 

Sounds good on paper but... That was a fail. The styrene sheet curls every way you don't want it to.  

 

 

 

 

[Handy Don 15,949]

So maybe the sheet needs the form mold on one side and a conformal pressure on the other side to keep it tight to the mold?

My friend the kayak maker had a bunch of cloth sacks filled with lead shot that he’d put onto the curved decks as he edge-glued the strips. With the curved surfaces, clamps just didn’t work. 

[ebinmaine 77,349]

6 minutes ago, Handy Don said:

So maybe the sheet needs the form mold on one side and a conformal pressure on the other side to keep it tight to the mold?

 

 

I believe this to be true. 

 

It seems that the sheet would need equal pressure on & from each side.  

 

[ebinmaine 77,349]

Did some sanding on the filler. 

Also trimmed the back panel and got some measurements. 

Hoping @Wheel Horse 3D can help me out.  

 

 

 

[ebinmaine 77,349]

Priming has begun.  

 

 

[ebinmaine 77,349]

On this trailer model there was a bent/broken spare tire holder.

 

I separated the pieces, made a "shop repair" and glued them together.

 

After gray paint I think it'll look good.  

 

 

 

[ebinmaine 77,349]

Got the spare tire holders painted. 

 

 

 

I left them a little rough because I'll be adding a "mud" colored layer. This model will be slightly weathered.  

 

************************************************

 

Also did some wet sanding on the tank surface. 

Gotta say... very impressive! 

 

In this pic you can see the gray areas where the uneven surfaces were/are. 

 

 

While I don't need this to be glass smooth  - I'm having fun experimenting with the primer and its capabilities.  

 

It'll get another several thin coats when the wind calms.  Then in a day or three another sanding.  

 

[ebinmaine 77,349]

Because I'm adding two rear sections of the tank together there was a gap at the very back bottom of the trailer.  

 

 

 

I used sheet styrene to fill the area. Two small pieces for the sides and a larger section in the middle.